A gamma ray detector is a detector used in nuclear medicine imaging equipment for early diagnosis of various diseases. It provides functional and biochemical images of human organs by detecting a gamma ray produced from a gamma ray source administered to patients.
Nuclear medicine equipments recently made a large contribution in the rapid development of molecular imaging area. These kinds of equipment are largely classified into Single Photon Emission Computerized Tomography (SPECT) using single photon and Positron Emission Tomography (PET) using two photons at the same time. As the detector technology evolved from PMT (photo multiplier tube) to semiconductor technology based solid-state methods, it provided many advantages such as improved quality of image, miniaturization of detector, and reduced installation space. However, it is particularly important to maintain a constant temperature of photoelectric sensors according to changing signal to noise ratio in the solid-state method, which are sensitive to temperature fluctuations. Further, some solid-state sensors can function normally at very low temperatures (−10° C. ˜−20° C.).
Therefore, many cooling techniques have been suggested, but most of them have shown to be not practical in terms of their effectiveness nor economical. Moreover, moisture and condensation generated during cooling to a low temperature have become problematic for radiation detectors using such semiconductor methods.